Evaluation of the wire flexibility used in the Mandibular Advancement Device submitted to thermal cycling / Avaliação da flexibilidade do fio utilizado no Dispositivo de Avanço Mandibular submetido ao ciclagem térmica

Este estudo teve como objetivo avaliar a flexibilidade de fios utilizados na confecção de molar lock do Mandibular Advancement Device (MAD), submetidos à variação de temperatura. Foram utilizados 64 segmentos de fios ortodônticos (n = 8), assim alocados: G1) Dentauro; G2) Leoni; G3) Leoni (Bio Steel); G4) Morelli; G5) Dentaurum + Termociclagem (TC); G6) Leoni + TC; G7) Leoni (Bio Steel) + TC; G8) Morelli + TC. Os segmentos foram analisados pelo método de flexão em três pontos, com auxílio de Máquina Universal de Ensaios. Os grupos submetidos à termociclagem foram submetidos a um total de 2300 ciclos térmicos (5 ° C e 55 ° C) correspondentes a 8 meses. Após esse período, os corpos-de-prova foram novamente imersos em água destilada a 37 ° C e mantidos em estufa por 24 horas. A partir desse processo de termociclagem, as amostras foram submetidas a um ensaio de flexão em três pontos. Os dados foram submetidos à análise de variância (ANOVA-two-way) seguida do teste de Tukey, considerando o nível de significância de 5%. Não houve diferença significativa na flexibilidade entre os grupos com e sem ciclismo, considerando a mesma marca e mesmo ponto (p = 0,05). Sem pedalar, a marca Dentaurum apresentou maior flexão média no ponto de 0,5mm, e Morelli apresentou maior flexão no ponto de 1,0mm (p <0,05). A marca Leoni apresentou valores maiores em 2 e 3 mm, e maiores que a marca Dentaurum no ponto de 2 mm (p <0,05). Para os grupos submetidos à termociclagem, nos pontos de 0,5 mm, não houve diferença estatística entre os grupos, exceto para o grupo Leoni, obtendo maior resistência à flexão em relação ao fio da marca Dentaurum (p <0,05). Em 1, 2 e 3 mm, o fio da marca Leoni apresentou maior flexibilidade em relação ao Dentaurum e Leoni (Bio Steel) e Morelli (p <0,05). A variação da temperatura não influencia nas propriedades de flexibilidade dos fios utilizados na confecção do MAD, porém, existem diferenças entre as diferentes marcas quando avaliadas nas mesmas condições

Seleção de agentes alternativos ao ágar para propagação de plântulas de Cattleya loddigesii Lindley (Orchidaceae)

The aim of this study was to evaluate the in vitro growth of Cattleya loddigesii in alternative agents to agar with starch and physical matrix with acclimatization of regenerated plants. Protocorms with 90 days after sowing (0.5 cm of length) were subcultured in 1/2 MS culture medium among the treatments consisting of: agar 7 g L-1 (T1, which corresponds the control), agar 3,5 g L-1 with cassava starch 30 g L-1 (T2), cassava starch 60 g L-1 (T3), cotton fiber (T4) and chopped polyurethane foam (T5). Plantlets were retained in these treatments for over 150 days, and at the end of in vitro culture, were analyzed by their biometric data and acclimatized in a greenhouse during 120 days and evaluated the survival and relative growth rate (RGR). The substrate comprising of chopped polyurethane foam (T5) showed greater efficiency for growth in vitro and also increased survival rate, while substrate cassava starch (T3) provided delay for plantlet growth. Therefore, chopped polyurethane foam is recommended because of low cost and suitable characteristics for the propagation of Cattleya loddigesii

Cryopreservation, early seedling development, and genetic stability of Oncidium flexuosum Sims

An efficient cryopreservation protocol was developed for mature seeds of Oncidium flexuosum Sims. Seed morphology, protocorm formation, and early seedling development were also assessed. The effects of phloroglucinol and Supercool X-1000® as cryoprotectant additives in the vitrification solution were investigated. Dehydration using the plant vitrification solution 2 (PVS2) for 60 and 120 min prior to immersion in liquid nitrogen promoted the highest frequency of in vitro seed germination 6 weeks following culture on half-strength Murashige and Skoog (1/2 MS) medium. Mature seeds submitted to vitrification for 120 min in PVS2 and 1 % phloroglucinol at 0 °C enhanced germination by 68 %, whereas in PVS2 and 1 % Supercool X-1000® germination was just moderately enhanced (26 %). In vitro-germinating seedlings developed healthy shoots and roots without the use of plant growth regulators. After 6 months of growth, there were no differences between in vitro- and ex vitro-grown seedlings for various phenotypic characteristics, including shoot length, number of leaves, number and length of roots, and fresh and dry weight. Seedlings were transferred to greenhouse conditions and successfully acclimatized, further developing into normal plants with over 90 % survival. Comparative analysis of seedlings from control and vitrified seeds using flow cytometry indicated that no change in ploidy levels occurred as a result of cryopreservation, therefore maintaining seedlings genetic stability. In this study, vitrification with PVS2 for 120 min with the addition of 1 % phloroglucinol offers a simple, safe, and feasible protocol for cryopreservation of O. flexuosum mature seeds. © 2013 Springer Science+Business Media Dordrecht